Plasma citrulline is not a biomarker for intestinal adaptation in short bowel syndrome, studied in piglets: a model for human neonates.

Background: There are no in vivo methods to measure adaptation in neonatal short bowel syndrome (SBS). We evaluated citrulline (Cit) levels in neonatal piglet surgical models of SBS.
Methods: Piglets underwent 75% mid-intestinal resection with jejunoileal anastomosis (JI), 75% distal resection of ileum with jejunocolic anastomosis (JC) or sham surgery. Jugular and gastric catheters were inserted for parenteral and enteral nutrition. On D7, small intestine length and weight were measured, jejunum collected for histopathology and Cit level determined.
Results: JI (n = 5) compared to JC (n = 5) had increased small intestinal length (JC - 17.5 cm; JI +22.0 cm; p = 0.02) and mass (JC 43.1 mg/cm/kg; JI 51.3 mg/cm/kg; p = 0.02), while Cit did not differ (JI 801.0 µM; JC 677.7 µM; p = 0.90). Including non-resected shams (n = 4), Cit correlated with length (R ²  = 0.48; p = 0.006), but not for SBS alone (R ²  = 0.11; p = 0.4), mass (R ²  = 0.05; p = 0.5). A second experiment compared change in Cit levels from baseline to D7. Levels declined in sham (n = 8) and JC (n = 10) (sham - 110.1 µM; JC - 56.6 µM; p = 0.17), regardless of intestinal lengthening (sham 29.9 cm; JC - 10.4 cm; p = 0.002).
Conclusion: Citrulline levels predict large differences in intestinal length and 'identify' SBS. However, citrulline cannot discriminate between adaptation in JI and JC, nor predict intestinal lengthening.